Women are highly susceptible to diseases associated with an unbalance in bone metabolism such as osteoporosis, particularly after menopause when female hormones decrease. People affected with osteoporosis are highly susceptible to bone fractures due to the low density of their bones. Elderly people, in particular, can become bedridden due to these bone fractures. Prevention of these problems has been strongly demanded.
Since raising bone density by improving the bone metabolism is desirable for such people having a tendency toward a decrease in bone density, there are some reported technologies with an object of improving bone metabolism. For example, the calcium absorption promotion effect of soy milk and the calcium absorption promotion substance in soy milk have been reported in Japanese Patent Application Laid-open Nos. 1994-46797 and 1995-75525, and the like. However, a satisfactory effect has not yet been achieved.
It has also been reported that isoflavone and a composition consisting of isoflavone and zinc or a peptide increase bone metabolism (Japanese Patent Application Laid-open Nos. 1998-114653 and 2000-139411). However, obtaining these components requires a complicated process. Although the isoflavone or the composition may be used as a medicine, it is difficult to say that the isoflavone or composition is suitable for use in applications to be taken continuously during routine life for improving bone metabolism.
At present, a method for improving bone metabolism satisfying all the characteristics of efficacy, economy, and ease of ingestion is not provided. An object of the present invention is to provide such a method.